Hello,

I've attached a sample solution in order to reproduce this problem.
Steps to reproduce:

1. Run the solution
2. Type any text like "Test"
3. Click on the "List" button to apply the "Bullet" list style
4. Hit enter in order to add another item to the list
5. Delete the entire list by pressing backspace all the way to the beginning of the document, and then press backspace again
6. Type "test" again
7. Click the "List" button to apply the "Bullet" list style
You will notice a very strange indentation of the list AND that you cannot add subitems to the list. The symbol will change but it will not get indented.

The above way of deleting a list, using backspace, is very common for the end users. And if they delete the list that way, they will no longer be able to create proper lists with proper indentations.

Let me know if you need more details about the issue